Data logging and video review.

What a logger records

Wikipedia describes motorsport data loggers as recording braking points, lap and sector times, track maps and readings from on-board sensors. Its telemetry article lists items such as three-axis acceleration, temperatures, wheel speeds and suspension movement, and in Formula One also the driver's inputs, which teams use to judge performance. Wikipedia also records that the FIA first allowed two-way telemetry (changes sent from the pits to the car) in Formula One in May 2001 and banned it from the 2003 season.

The channels a driver needs

Driver61 says the most important logged channels for a driver are four:

• Speed
• Throttle position
• Brake pressure
• Engine RPM

Systems range from GPS-only units to setups with hundreds of channels, and Driver61 says the extra channels mainly serve engineers. For drivers it recommends a GPS-based logger paired with video cameras, so the numbers and the footage can be reviewed together.

What to look for

Where to spend your effort

HP Academy says decisions about which corners to prioritize should come from data, because a track map and a few laps are not enough. Without a logger, it offers a rough alternative: compare speed at a fixed point on the following straight while trying different approaches to the corner. Driver61 suggests watching the lap delta to see where time is being gained when conditions are changing. How to choose priority corners is covered on learning a track.

Braking and throttle traces

Driver61 describes four phases in a brake trace: a quick move from throttle to brake, a build to maximum pressure, modulation near the grip limit, and a smooth release toward turn-in. It lists the common braking mistakes as a slow throttle-to-brake transition, inconsistent pressure, and braking too early or too late. Braking itself is covered on braking.

On the throttle, Ross Bentley says getting back to it earlier does not automatically mean a better exit. What matters most, in his view, is when the driver reaches full throttle, not when the pedal is first touched. HP Academy notes a detail that is easier to see in data than to feel: small dips in brake pressure during a heel-and-toe blip usually only show up in the logs (see heel-toe).

The G-G plot

Plotting lateral against longitudinal acceleration gives a picture of the friction circle. Brian Beckman notes in The Physics of Racing that a whole car's traction budget is often egg-shaped rather than circular, for example flattened at the top where acceleration is limited. Adam Brouillard (Paradigm Shift Driver Development) says most cars' plots look like a circle with part of the top missing, and that the lower a car's acceleration relative to its grip, the more is missing.

Brouillard also cautions against reading too much into the shape. A well-rounded plot shows good car control, he says, but does not by itself prove good corner entry, because what matters is being at the right point on the circle at the right time. The physics is covered on weight transfer.

Video

Video is part of how coaching is delivered. Blayze, the coaching platform co-founded by Dion von Moltke, builds its model around one-on-one, video-based instruction from professional drivers, including analysis of pole-lap onboard footage. HP Academy recommends watching professional onboard footage when learning where a track's apexes are.

Our research did not include a coach-written method for camera placement or a step-by-step data review routine, so this page does not offer one. Check the event's rules and tech requirements before mounting a camera or logger in the car.

Review without data

Structured review does not need a logger. NASA's HPDE pairs in-car instruction with classroom debriefs it calls "download" meetings, and SCCA Time Trials strongly suggests post-session debriefs for novices. Ross Bentley's advice applies either way: be consistent at the limit before making big car changes, so you can tell whether a gain came from the car or the driver, and be honest about whether you actually felt a difference.